#include<unistd.h>
#include<stdio.h>

int main()
{
    pid_t pid;
    printf("Before: pid is %d\n",getpid());

    if((pid=fork()) == -1 )
    {
        perror("fork()");
        exit(1);
    }
    printf("After:pid is %d, fork return %d\n", getpid(), pid);
    sleep(1);
    return 0;
}